*Projection assumes annual inflation adjustments to withdrawal amount.
function calculateWithdrawalLogic() {
// 1. Get input values
var portfolio = parseFloat(document.getElementById('portfolioValue').value);
var withdrawal = parseFloat(document.getElementById('annualWithdrawal').value);
var returnRate = parseFloat(document.getElementById('investmentReturn').value);
var inflation = parseFloat(document.getElementById('inflationRate').value);
// 2. Validate inputs
if (isNaN(portfolio) || portfolio <= 0) {
alert("Please enter a valid Portfolio Value.");
return;
}
if (isNaN(withdrawal) || withdrawal < 0) {
alert("Please enter a valid Withdrawal Amount.");
return;
}
if (isNaN(returnRate)) returnRate = 0;
if (isNaN(inflation)) inflation = 0;
// 3. Calculate Immediate Withdrawal Rate
var rawRate = (withdrawal / portfolio) * 100;
var formattedRate = rawRate.toFixed(2) + "%";
// 4. Determine Sustainability Status (Based on Trinity Study / General Guidelines)
var statusText = "";
var statusClass = "";
if (rawRate <= 3.5) {
statusText = "Very Safe (Conservative)";
statusClass = "status-safe";
} else if (rawRate <= 4.0) {
statusText = "Safe (Standard 4% Rule)";
statusClass = "status-safe";
} else if (rawRate <= 5.0) {
statusText = "Caution (Risk of Depletion)";
statusClass = "status-caution";
} else {
statusText = "High Risk (Unlikely to Last)";
statusClass = "status-danger";
}
// 5. Calculate Years Until Depletion (Simulation Loop)
// Logic: Iterate year by year.
// Balance grows by Return Rate. Withdrawal increases by Inflation Rate.
// Subtract withdrawal from balance.
var currentBalance = portfolio;
var currentDraw = withdrawal;
var years = 0;
var maxYears = 60; // Cap calculation at 60 years
var depleted = false;
// Using simple annual compounding simulation
while (years < maxYears) {
// Apply Growth
currentBalance = currentBalance * (1 + (returnRate / 100));
// Subtract Withdrawal
currentBalance = currentBalance – currentDraw;
// Adjust Withdrawal for Inflation for next year
currentDraw = currentDraw * (1 + (inflation / 100));
years++;
if (currentBalance <= 0) {
depleted = true;
break;
}
}
var yearsText = "";
if (depleted) {
yearsText = years + " Years";
} else {
yearsText = "60+ Years (Perpetual)";
}
// 6. Display Results
document.getElementById('rateResult').innerHTML = formattedRate;
var badge = document.getElementById('statusBadge');
badge.innerHTML = statusText;
badge.className = "status-badge " + statusClass;
document.getElementById('yearsResult').innerHTML = yearsText;
document.getElementById('resultContainer').style.display = "block";
}
How to Calculate Retirement Withdrawal Rate
Understanding your retirement withdrawal rate is one of the most critical steps in ensuring your savings last throughout your golden years. This metric represents the percentage of your total investment portfolio that you withdraw annually to cover living expenses.
Calculating this rate accurately helps you determine if your spending habits are sustainable or if you run the risk of outliving your money. Financial experts often reference the "4% Rule," but your personal rate depends on market conditions, inflation, and your time horizon.
The Formula
The basic calculation for your current withdrawal rate is straightforward:
For example, if you have $1,000,000 saved and you withdraw $40,000 per year, your withdrawal rate is 4%.
What is a Safe Withdrawal Rate?
While the "4% Rule" (derived from the Trinity Study) is a popular benchmark, modern economic conditions have led some advisors to suggest more conservative rates.
3% to 3.5%: considered very conservative and safe, ideal for early retirees (FIRE movement) looking for a 40+ year horizon.
4%: The traditional standard. Historically, this rate has allowed portfolios to last 30 years in most market scenarios.
5% and above: Considered risky. While feasible during bull markets, a 5%+ withdrawal rate significantly increases the sequence of returns risk, where a market downturn early in retirement depletes capital too fast to recover.
Factors That Affect Sustainability
Several variables impact how long your money will actually last, which is why our calculator includes inputs for return and inflation:
Sequence of Returns Risk: Experiencing a market crash in the first 5 years of retirement is far more damaging than a crash 20 years later.
Inflation: Your withdrawal amount isn't static. It needs to increase every year to maintain purchasing power. A 3% inflation rate doubles your cost of living approximately every 24 years.
Asset Allocation: A portfolio heavily weighted in stocks typically offers higher growth but more volatility, while bonds offer stability but lower returns.
How to Use This Calculator
Use this tool to stress-test your retirement plan:
Enter your total liquid investment savings (do not include home equity unless you plan to sell).
Enter your projected annual spending needs from this portfolio (subtract Social Security or pension income from your total expenses first).
Adjust the expected return and inflation rates to see how sensitive your plan is to economic changes. Conservative estimates are 5-7% for returns and 2-4% for inflation.